<nav class="navbar bg-body-tertiary">
    <div class="container-fluid">
        <span class="navbar-brand">新闻后台管理端</span>
        <div>
            <img src="" alt="" id="topbar-photo" style="width:40px;border-radius: 50%;height: 40px;">
            欢迎
            <span id="currentUsername">aaaa</span>
            回来
            <button type="button" class="btn btn-danger" id="exit">退出</button>
            <a  class="btn btn-secondary" id="logIn" href="/code/web/view/products/index.html">回到主页面</a>
        </div>
    </div>
</nav>